The Ironweed Persists!

For several years now, while walking along the Burl Trail at Gray's Crossing near Ballston Spa, I have found two widely separated plants of Tall Ironweed (Vernonia gigantea) growing on the banks of the Kayaderosseras Creek. I again found the same two plants while walking there this week, towering among the nearly-as-tall thickets of Tall Goldenrod  and Mugwort that offer the Ironweed some serious competition.

Finding this lovely native species is quite a delight for me, since Vernonia gigantea is rated as an Endangered species in New York State. Back in 2011, I reported finding a single specimen of it growing in a sandplain restoration site some miles away in Wilton, but unfortunately, that plant was subsequently mowed down by road crews, never to reappear. I first found the two specimens along the Burl Trail in 2017, so I am delighted to discover that they have persisted at this location now for six years. 

To better enjoy the colorful beauty of these Tall Ironweed flowers, I had to bend the flower stalk down to my eye level. This gigantic native wildflower is very aptly named!

The chances are good that the Tall Ironweed arrived at this location when the state's Department of Transportation, during a flood-control project, denuded, re-shaped, and subsequently reforested the banks of the Kayaderosseras back in 2012, thus introducing a number of otherwise disjunct plant species to this location. The Burl Trail is part of the Saratoga Spa State Park, and thus is state property. I am hoping our state botanists might want to record the location of these Endangered plants -- and perhaps undertake some efforts to preserve their presence at this site. Unfortunately, the streambank restoration undertaken by the DOT introduced not just native trees, shrubs, and wildflowers but, inadvertently, also a number of very invasive species, Wild Chervil and Mugwort being the worst of them.

One of the ways to distinguish this Endangered species of Tall Ironweed from the more common species called New York Ironweed (V. noveboracensis), is to observe the bracts on the flowers' involucres. Although Tall Ironweed's bracts are sharply pointed, they do not extend into long threadlike projections, as do those of the New York Ironweed. Here is my photo of the bracts on the Tall Ironweed involucres:

And here is my photo of the long threadlike bracts on the involucres of New York Ironweed. I believe the difference is obvious.

According to Newcomb's Wildflower Guide, an even more accurate way to distinguish the two species is to dismantle a flower and count the number of florets that make up each flower.  I did dismantle a flower of the specimen I found along the Burl Trail this week, and the 23 florets puts the number well within the limit for Vernonia gigantea, which is 13 to 30 florets.  The distinguishing number of florets for V. novaeboraecensis (according to Newcomb) is 30 to 50.

 So I do feel confident to state that two specimens of the Endangered species called Tall Ironweed does grow at this location.  I hope it will persist.